The present invention relates generally to the chemical arts and more particularly to thixotropic oil and/or resin-based ink compositions and methods of preparing same.
Various printing ink compositions have heretofore included thixotropic chemical compounds and/or organophilic clay gelant materials for purposes of imparting desired thixotropic properties to the ink. However, many chemical compounds used as thixotropic agents of the prior art require the application of substantial heat in order to obtain the desired rheological properties. Additionally, clay-type thixotropic agents tend to swell as they absorb oil and, because clay thixotropic agents are generally prepared in powder form, they often require vigorous mixing in order to obtain a final smooth ink composition. Such clay-type thixotropic agents also greatly reduce the gloss of certain heatset inks.
Accordingly, there exists a need in the art for improved thixotropic agents for use in organic-based (e.g. oil-based, resin-based) ink systems. It is desirable that such improved thixotropic agents be easily misable or dissolvable in organic ink vehicles. Additionally, it is desirable that such improved thixotropic agents be usable at room temperature or at normal ink manufacturing/processing temperatures without the necessity of increasing such temperatures to gain effective thixotropic effects. Furthermore, any such thixotropic agents should not diminish or detract from any desirable physical, chemical, and visual properties of the ink compositions in which they are incorporated.